The explosive era in both Irish history and Yeats's poetry justify the length of the second volume of Oxford historian Foster's masterful life of Yeats. Again Foster approaches Yeats's memoirs with skepticism, shrewdly and scrupulously applying the historical facts to Yeats's self-made image and his poetry. The result adds a unique, superb perspective on Yeats's poetic treatment of the Easter Uprising and subsequent civil war, his eventual disenchantment with the new Irish Free State and the restless philosophical questing of his last years, up to his death just before Ireland's break from Great Britain in WWII. Following Responsibilities in 1914, Yeats had hoped to start a domestic phase in his life with his marriage to Georgie Hyde-Lees and his homesteader purchase of Ballylee castle. Instead, this time of upheaval saw him apotheosize two martyrs, Maude Gonne's husband in "Easter 1916," and Great War casualty Robert Gregory, in "An Irish Airman Foresees His Death." Foster's consummate treatment of the Irish Free State's violent birth further illuminates Yeats's best work in The Wild Swans at Coole and The Tower with a vividness rarely found in biography. More personal matters, such as automatic-writing séances with his wife and his theosophical treatise The Vision, are of less interest to the historian-biographer than Yeats's public figure, including his battles with Catholic censorship and his dubious but brief association with the "Blueshirt" fascist faction. Even as history caught up with and overtook the Free State senator and Nobel laureate, Foster splendidly rounds out the Celtic Twilight bard's inner revolution in his magnificent twilight years. (Nov.)